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U040D Invalid Data Received From Turbocharger/Supercharger Control Module A

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

Turbocharger/supercharger control module A is in practice an electronic charger actuator that sets the vanes of a variable-geometry turbine or a wastegate on command and reports position and status back. U040D means those reports arrive but the engine controller judges them invalid. No manufacturer documents U040D publicly. The module is documented through its lost-contact code U010C: GM's 2017 small-diesel table expects its frames on a dedicated sensor bus, and FCA replaced the turbo actuator of 2015 Ram 2500/3500 trucks with the 6.7 L Cummins under a warranty extension when U010C came with boost codes (09-005-22). With invalid actuator data the boost loop cannot be closed with confidence, so the controller usually caps boost and torque; boost control is emission-relevant under CARB, so a MIL is likely. U040E is module B.

Likely causes

Electronics of the turbo actuator degraded by heat
Sticking vanes or linkage making the actuator report implausible positions
Connector or sensor bus line at the actuator damaged

Symptoms

  • Check engine light
  • Noticeably reduced power (limp mode)
  • Boost pressure codes stored alongside

Repair estimate

DifficultyHardWorkshop job
Parts and labour€150–1,800
Time1–4 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

boost control module a

Related codes

U010CU040EP0046P0234

References: gsi.ext.gm.com, static.nhtsa.gov, law.cornell.edu.